NZ202333A

NZ202333A - Gasifying carbonaceous material

Info

Publication number: NZ202333A
Application number: NZ202333A
Authority: NZ
Inventors: B Johansson; S Santen
Original assignee: Skf Steel Eng Ab
Priority date: 1982-03-01
Filing date: 1982-11-01
Publication date: 1984-11-09
Also published as: BR8206416A; CA1208021A; NL8203909A; KR880000353B1; ATA364182A; DE3233774C2; PL239081A1; IN156382B; IT1153274B; DD208986A5; FR2522333A1; NO158066B; MX161612A; ES8400477A1; PL135926B1; AU546482B2; AU9002682A; YU235382A; PH18531A; NO823341L

Description

<div class="application article clearfix" id="description"> 202333 Priority C'cCi-c}: .». Convicts 72-.C: I Cisco: PukUcdlcp. Ojiz: ... > fi.9 .NOW 4984 P.O. Journd, L j: « »•..« NEW ZEALAND PATENTS ACT 1953 PATENTS FORM NO.5 COMPLETE SPECIFICATION "GASIFYING CARBONACEOUS MATERIAL" WE, SKF STEEL ENGINEERING AB, A Swedish Company, (Sweden) P.O. Box 202, S-813 00 Hofors, Sweden, hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: - 1 - 2023 3 3 The present invention relates to a method and means for gasifying carbonaceous material to a gas mixture consisting primarily of CO and and preferably having a total content of CO^ and less 5 than 12%. It has long been known to gasify carbon in shaft furnaces and retorts and also to perform partial gasification in conjunction with coking. The drawback with the known methods is partly that it has been 10 impossible to regulate the ratio between CO and H2 in the gas produced but, most important, that the gas also contained a number of undesirable substances such as hydrocarbon, alcohols, phenols and tar. The latter is obtained primarily because the gasification takes 15 place at low temperature, i.e. at temperatures lower than 1000°C and under reducing conditions. In order to remedy these drawbacks, other methods have been developed where the gasification takes place under high temperature and oxidizing 20 conditions, such as the Koppers-Totzek method. However, this method has the disadvantage that, due to the thermodynamic equilibrium, the 1^0 content becomes - 2 - 0 ? 3 j 3 relatively high which means that, to enable it to be used for reducing iron ore, for instance, the gas produced in this way must first be cooled, washed and then re-heated. Furthermore, the chances of 5 influencing the ratio between CO and H2 leaving the gasifier is extremely slight according to this method. In accordance with the present invention there is provided a method of gasifying carbonaceous material to a gas mixture containing primarily CO and 10 which comprises 1) supplying carbonaceous material in lump form via a sluice arrangement to a reactor, preferably a shaft furnace, from above to a predetermined filling level, 2) withdrawing gas generated from the reactor through an outlet at a level below the upper 15 surface of the carbonaceous material and 3) supplying oxidant and/or thermal energy both above the surface of the carbonaceous material and at a lower level in the reactor below the level of the gas outlet. In the method of invention the gasification 20 occurs at high temperature and under oxidising conditions and at the same time the gas initially produced passes a hot bed of carbonaceous, e.g. coke or a cokelike, material, whereupon its content of I^O reacts with carbon to form and CO. Furthermore, the method according to 25 the invention enables the CO/H2 ratio to be controlled since thermal energy can be supplied via plasma - 3 - generators so that the ratio between H20, CO2 and 02 in the oxidizing gas can be varied within wide limits. Preferably the ratios_are controlled such that the CO/H2 ratio is less than 12%. 5 The invention will be described in more detail in the following with reference to two embodiments shown in the accompanying drawings, in which Figure 1 is a diagram of apparatus according to the invention, and 10 Figure 2 shows an alternative embodiment of the apparatus shown in Figure 1 with respect to the lower part of the reactoro The apparatus shown in Figure 1 and the alternative in Figure 2 consist of a shaft furnace 1, 15 provided at the bottom with tuyeres 2 and plasma generators 3, preferably located symmetrically around the shaft 1. These tuyeres are provided with feeding means for oxidant such as oxygen (or gas containing oxygen), H20 or C02 and possibly also powdered 20 carbonaceous material. At a higher level the shaft 1 is provided with an annular drum 4 with a gas outlet 5 for the withdrawal of gas produced in the shaft. At the top the shaft 1 is provided with a gas-tight sluice arrangement 6 for the supply of carbonaceous material 25 in lump form and also with a tuyere for connection of a plasma generator 7 and feed-in lances 8, 9 for - 4 - 202333 oxidant. Supply means 11, 12 for the supply of extra oxidant if necessary open into the shaft at a level between the upper surface 10 of the solid material in the shaft 1 and the annular drum 4. To enable the 5 process to be driven with liquid slag or solid ash, the bottom part of the shaft 1 is provided with either a tapping channel 13 (Figc 1) for slag or a rotating feed-out table 14 (Fig« 2)o The apparatus shown in the drawings operates 10 as follows: To achieve the desired gasification the carbonaceous material in lump form is fed in, possibly together with a sulphur-binder e.g. material in lump form containing Ca and/or Mg such as dolomite, via the 15 sluice 6 into the shaft I to a predetermined level. Thermal energy is supplied by means of one or more plasma generators 3 and 7, respectively, at the same time as oxidant such as 0^, CO2 or I^O is supplied via supply means 2 and 8, 9, respectively. The carbonaceous 20 material in lump form, which may consist entirely or partially of coal, coke, pressed coke, peat, lignite, charcoal, wood or partially charred wood, etc., is thus subjected to high temperature under oxidizing conditions, whereupon the volatile constituents are released and 25 react with the oxidant producing primarily CO and H2, while the non-volatile part is coked and forms a solid - 5 - 2023 33 cokelike product in lump form. It is desirable that an excess of oxidant is added in order to prevent the formation of soot. The oxidant supplied above the surface of the carbonaceous material should preferably I 5 be sufficient at least to partially oxidise the volatile constituents of the carbonaceous material. Oxidant which has not reacted with the volatile constituents of the carbonaceous material will react lower down in the shaft 1 with the coke produced, forming additional CO 10 and possibly I^O. The products formed in the upper part of the shaft, above the level of the annular drum 4. are thus products similar to coke which continue down through the shaft and a gaseous product consisting primarily of CO and which leaves the shaft 1 15 through the annular drum 4, which is preferably more than 50 cm below the level to which the carbonaceous material is filled* The temperature on the surface of the granular material in the shaft may reach about 2000°C, while the gas leaving the shaft via the annular 20 drum 4 has a maximum temperature of 1500°C. It is also possible to supply the necessary thermal energy by partial combustion of the carbonaceous material with oxygen instead of using a plasma generator. A number of tuyeres 2 are placed around the lower part of the 25 shaft 1, said tuyeres being provided with either plasma generators or supply means for oxygen as well as supply 3 ^ means for oxidant and possibly powdered carbonaceous material and possibly also powdered material containing Ca and/or Mg to bind sulphur. At this level, preferably approximately 100cm lower than the level of the annular 5 drum 4, both the cokelike material falling down through the shaft and any powdered carbonaceous material blown in will be completely gasified. Any CO^ and leaving the reaction zone just before the tuyere will react further up in the shaft with the lump material 10 on its way down, producing primarily CO and The gas produced, consisting primarily of CO and H2, will leave the shaft through the annular drum 4- Preferably the gasification takes place under a pressure exceeding atmospheric pressure. 15 It may be advisable to supply slag-former at this level through the material lances 2, and to regulate the viscosity and melting point of the slag and/or sulphur absorbants containing Ca and/or Mg, such as dolomite powder. By controlling the composition of 20 the slag in this way, it can be made suitable as a raw product for the manufacture of cement. It is also possible to replace the supply of heat via plasma burners at this level by partial combustion of the carbonaceous material by means of oxygen. 25 If it is desired to produce a liquid slag from the ash content so that it can be tapped off, the - 7 - 2Q7 3 :$ 3 temperature in the reaction zone in front of the tuyeres 2 in the lower part of the shaft should be maintained at above 1600°CW Preferably such liquid slag is granulated and rapidly cooled as it is being 5 tapped off. When running the plant with solid ash which can be fed out as a solid by-product, this temperature should be kept below 1400°C. Control of the supply of thermal energy enables these temperatures to be controlled. 10 The method described here for gasifying carbonaceous material offers considerable possibilities for regulating the li^/CO ratio in the gas produced, partly since the ratio of CO/H^O in the oxidant can be regulated and partly by sharing the heat supply between 15 partial combustion and via plasma generators. The matter contained in each of the following claims is to be read as part of the general description of the present invention. - 8 - </div>

Claims

<div class="application article clearfix printTableText" id="claims"> 202333 WHAT WE CLAIM IS:

1. Method of gasifying carbonaceous material to a gas mixture containing primarily CO and , which comprises (1) supplying carbonaceous material in lump form via a sluice arrangement to a reactor from above to a predetermined filling level ,(.2) withdrawing gas generated from the reactor through an outlet at a level below the upper surface of the carbonaceous material and (3) supplying oxidant and/or thermal energy both above the surface of the carbonaceous material and at a lower level in the reactor below the level of the gas outlet.

2. Method according to claim 1 in which the reactor is a shaft furnace.

3. Method according to claim 1 or 2 in which the gas generated is withdrawn from the reactor at a level more than 50 cm below the level to which the carbonaceous material is filled.

4- Method according to claim 1, 2 or 3 in which the oxidant and/or thermal energy is supplied to the reactor at a level about 100 cm lower than the level at which the gas is withdrawn.

5- Method according to any one of the preceding claims in which ^O, CO^ and/or gas containing oxygen is used as oxidant.

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6. Method according to any one of the preceding claims in which the thermal energy is supplied by a gas which is caused to pass a plasma generator.

7. Method according to any one of claims 1 to 5 in which thermal energy is supplied through partial combustion of the carbonaceous material.

8. Method according to any one of the preceding-claims in which-the oxidant supplied above the surface -of-- the carbonaceous material is sufficient,-at least-"partially, to oxidise volatile constituents of the carbonaceous material. *

9. Method according to any one of the preceding^claims^in. v/hich the quantities -of H-^O, gas containingroxygen and/or- CO^ in the oxidizing^gas -are— controlled so ?as to control the H^/CO ratio-in the-gas—— produced^ _

10. Method according to claim 9 in which the -f^/CO ratio in the gas produced is less than 12%.

11. Method according to any one of the preceding claims in which powdered carbonaceous material is injected at the lower level in the shaft, together with the oxidant and/or thermal energy.

12. Method according to any one of the preceding claims in which material in lump form containing Ca and/or-Mg is added together- with■ the carbonaceous---- -

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material in lump form in order to bind sulphur.

13. Method according to claim 11 in which powdered material containing Ca and/or Mg is added together with the powdered carbonaceous material in order to bind sulphur.

14. Method according to any one of the preceding claims in which the supply of thermal energy is controlled such that ash content in the carbonaceous material-forms a liquid-slag^which is .tapped off at the bottom of the reactor.

15. Method according to claim 14 in which slag-former is added to the carbonaceous material in order_to controlLthe Jiielting.point^and lyiscosity o.f the slag.

16. Method according to claim 14 or 15 in which slag-former is added to the carbonaceous material in order^to control-the composition - of the slag to be suitable for the manufacture of cement.

17. Method according to claim 14, 15 or 16 in which the liquid slag is granulated and rapidly cooled with water as it is being tapped off.

18. Method according to any one of claims 1 to 13 in which the supply of thermal energy is controlled so that ash content in the carbonaceous material remains

%

in solid phase and is fed out as a solid by-product from a-bottom part-of-the reactor.

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202333

19. Method according to any one of the preceding claims in which the carbonaceous material consists entirely or partially of coal, coke, pressed coke, wood, partially charred wood, charcoal, lignite or peat.

20. Method according to any one of the preceding claims in which gasification takes place under a pressure exceeding atmospheric pressure.

21. Method according to claim 1 substantially as hereinbefore described with reference to and as illustrated in either of the Figures of the accompanying Drawings.

22. Apparatus for carrying out the method as claimed in any one of the preceding claims, comprising a reactor in the form of a shaft furnace, having an upper sluice arrangement to enable carbonaceous material in lump form to be supplied in gas-tight manner to a predetermined filling level in the shaft, a slag-tapping means arranged at the bottom of the shaft, and an annular drum provided with a gas outlet for gas produced, said annular drum being arranged at a level below the predetermined level to which the solid material is filled.

23. Apparatus according to claim 22 also comprising means for the supply of thermal energy and/or oxidant arranged below the gas outlet and/or

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2023 3 3

above the level of the solid material.

24- Apparatus according to claim 22 or 23 also comprising plasma generators for the supply of the rma1 ene rgy.

25. Apparatus according to claim 22, 23 or 24 in which the slag-tapping means comprises a rotating feed-out table.

26. Apparatus according to claim 22 substantially as hereinbefore described with reference to and as illustrated in either Figure of the accompanying Drawings.

SKF STEEL ENGINEERING AB,

By Their Attorneys

HENRY HUGHES LIMITED

By: iiQwf

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